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Organic acids are considered to low gastric pH, thereby resulting in increased activity of proteolytic enzymes and gastric retention time. Citric acid (CA) has been studied in piglets improving performance and increased dry matter and protein digestibility. The aim of this study was to determine the effects of supplementation of 5, 10 and 15 g/kg CA in late gestation and lactation basal diets on sow and litter performance, coefficient of total tract apparent digestibility (CTTAD) of crude protein (CP), calcium (Ca) and phosphorus (P), plasma biochemistry parameters, colostrum and milk composition and immunoglobulin. Forty-eight sows (landrace × large white, mean parity 3.82 ± 1.00) were randomly allotted to four dietary treatments (n = 12 sows/treatment) supplemented with 0 (control), 5, 10 or 15 g/kg CA. The CA used for the experiment was citric acid monohydrate (purity: 99.5%). The experiment lasted from day 90 of gestation and until day 24 of lactation. Blood samples were collected on day 107 of gestation, day 0 (farrowing) and day 24 (weaning) of lactation. The colostrum and milk samples were obtained on day 0 and day 14 of lactation, respectively. Faecal samples were collected from the sows on days 20 and 21 of lactation.
The results showed that the CTTAD of Ca was significantly increased with 10 and 15 g/kg CA and supplementation of 15 g/kg CA increased the CTTAD of CP and P (P < 0.05). There were no differences in sow average daily feed intake (ADFI), sow body weight (BW) change, litter size, litter weight at birth and weaning and weight gain of the piglets. During the experiment, the Ca concentration of plasma was enhanced by adding 10 g/kg CA (P < 0.05). Supplementing CA increased the P concentration of plasma on day 107 of gestation (P < 0.05). The total protein (TP) of plasma on the days of farrowing and weaning and the TP of colostrum and milk were improved by adding 15 g/kg CA (P < 0.05). Supplementation of 10 and 15 g/kg CA improved the IgG and IgA levels in the plasma of sows. Immunoglobulin levels in colostrum and milk were significantly enhanced with 15 g/kg CA supplemented diets compared with the control (P < 0.05), with the exception of IgG of milk (P > 0.05).
In conclusion, dietary supplementation of CA during late gestation and lactation had no significant effects on sow and litter performance. Additions of 10 and 15 g/kg CA enhanced the absorption of dietary Ca, P and protein. Finally, supplementation of 15 g/kg CA increased concentrations of IgG, IgA and IgM in colostrum and IgA and IgM in milk, which might better protect humoral and mucosal immunity of piglets.
Liu, S.T., Hou, W.X., Cheng, S.Y., Shi, B.M. and Shan, A.S. 2014. Effects of dietary citric acid on performance, digestibility of calcium and phosphorus, milk composition and immunoglobulin in sows during late gestation and lactation. Animal Feed Science and Technology 191; 67–75. http://dx.doi.org/10.1016/j.anifeedsci.2014.01.017
